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Discussion Starter #1
As of now Im going for Timken's unless there's a better option. Does anyone know if this is the correct bearing for a 2015 850 sp ? m coming up with Timken # 510003 Wheel Bearing (full disclosure,,I have and always have had FOBO)
 

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What are the markings on the OEM bearing or what are the dimensions in mm (all bearings are metric unless they are special inch bearings - kinda like all spark plug threads are metric, but the socket to remove and install may be either inch or metric)
 

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As of now ,not a clue.I just saw the bearing was loose and needed replacement. This all started with wanting to pull the clutches to seal up the rear clutch cover .
 

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Crazyflyboy posted this last week. Made in Japan, as far as I’m concerned better than Made in China Timken bearings. Price is for 2 bearings!!! You can’t beat this price either:
 

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#3514699 ? Yes
Crazyflyboy posted this last week. Made in Japan, as far as I’m concerned better than Made in China Timken bearings. Price is for 2 bearings!!! You can’t beat this price either:
Ok Thanks Ill look into them What I see at a glance is Its recommended using loctite 603
Im not a mechanic but Iv never heard of using loctite 603 on bearings ?Is that something I should be doing?? AS far as price I dont know about bearings BUT IMO some things are definitely You get what you pay for
 

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Ive never heard of using Loctite either but it may be correct to do so. Also, KOYO Bearings are OEM for a few different Japanese Atv’s. I typically prefer Japanese made products over Chinese. From what I’ve been reading, all Timken are now made in China. I’d buy KOYO in a heartbeat but I have a Sportsman 570. I might contact them to see if they have other sizes. BTW- I looked up these KOYO Bearings and this place is selling them at basically 1/2 price. You can do all 4 for like $70.00. They have a 3 year warranty. I don’t think Timken does.
 

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Point: Polaris does not make bearings - they buy them from a bearing manufacturer, buy in bulk, possibly have the expense of packaging them in their own over-wrap and tack on a profit margin.

Point: The same size bearing may be manufactured to higher or lower quality standards including the materials, design and mass (more or less material).

Point: The bearing may or may not meet design specifications and the product may not be adequate for the application or the product may exceed the design specifications.

Cost is not always a good indicator of quality. If something is special, but mass produced it will cost less than a small quantity of a special production run.

Example: Honda specified a special design common bearing as the transmission shaft bearing on the sprocket end of the output shaft of XR400R motorcycles and TRX400EX quads through 2003 (in 2004 the bearing was re-spec'ed to a special size). The bearing part number 91003-KCY-671 is marked 6205R/2BHR measures 25x52x13 - a standard 6206 bearing measures 25x52x15 - this bearing (KOYO) is NLA. In late 2004 the bearing was changed to a 25x55x13 - the new bearing is part 91003-HN1-003 and is marked DG2555/13HR (KOYO). Since the early bearing is NLA and a standard 6205 cannot be used, it demands replacement with whatever fits the application. Two options; 1) re-machine the engine case to install the new 55 mm bearing in the case originally machined for 52 mm. 2) install a bearing from any source that measures the 25x52x13 dimension.

I found a Chinese bearing MOCHU marked 6205-13. The cost was not CHEAPER - the KOYO bearing from Honda was $24 - the MOCHU was $38 and the difference in quality is obvious - the MOCHU bearing uses smaller balls and shallow groves (less load carrying capacity), but the races are thicker - it fits the shaft and the hole for a direct replacement, but it will not last as many years and depending on the severity of use by the operator. The original bearing Honda installed would fail (breaking (splitting) the outside race which is why Honda increased the thickness of the outer race when the engine was redesigned in late 2004).

I ordered a special production run of (5) 25x52x13 bearings from MOCHU in China for $38 each, but got free shipping direct from Shanghi. They may not be the same quality, but it was the cheaper alternative to machine shop work and a faster repair to boot.

140199


140201


140203


140205
 

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Discussion Starter #9
Point: Polaris does not make bearings - they buy them from a bearing manufacturer, buy in bulk, possibly have the expense of packaging them in their own over-wrap and tack on a profit margin.

Point: The same size bearing may be manufactured to higher or lower quality standards including the materials, design and mass (more or less material).

Point: The bearing may or may not meet design specifications and the product may not be adequate for the application or the product may exceed the design specifications.

Cost is not always a good indicator of quality. If something is special, but mass produced it will cost less than a small quantity of a special production run.

Example: Honda specified a special design common bearing as the transmission shaft bearing on the sprocket end of the output shaft of XR400R motorcycles and TRX400EX quads through 2003 (in 2004 the bearing was re-spec'ed to a special size). The bearing part number 91003-KCY-671 is marked 6205R/2BHR measures 25x52x13 - a standard 6206 bearing measures 25x52x15 - this bearing (KOYO) is NLA. In late 2004 the bearing was changed to a 25x55x13 - the new bearing is part 91003-HN1-003 and is marked DG2555/13HR (KOYO). Since the early bearing is NLA and a standard 6205 cannot be used, it demands replacement with whatever fits the application. Two options; 1) re-machine the engine case to install the new 55 mm bearing in the case originally machined for 52 mm. 2) install a bearing from any source that measures the 25x52x13 dimension.

I found a Chinese bearing MOCHU marked 6205-13. The cost was not CHEAPER - the KOYO bearing from Honda was $24 - the MOCHU was $38 and the difference in quality is obvious - the MOCHU bearing uses smaller balls and shallow groves (less load carrying capacity), but the races are thicker - it fits the shaft and the hole for a direct replacement, but it will not last as many years and depending on the severity of use by the operator. The original bearing Honda installed would fail (breaking (splitting) the outside race which is why Honda increased the thickness of the outer race when the engine was redesigned in late 2004).

I ordered a special production run of (5) 25x52x13 bearings from MOCHU in China for $38 each, but got free shipping direct from Shanghi. They may not be the same quality, but it was the cheaper alternative to machine shop work and a faster repair to boot.
with that said is there a bearing you find better then oem?
 

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Yes - but it all depends on the purpose and application - and you can't make that decision based on price or brand name, you have to look at the bearing characteristics which includes materials, design and construction.

A ball bearing with a plastic ball retainer may be fine for a low speed application (I have seen this style bearing in industrial constant speed (500 RPM) gear boxes and lifting hoist transmissions and they may last a lifetime, but the same bearing will melt the retainer if used in a rotary screw compressor running at 5000 RPM.

Bearings are a whole science and people never think about the design or it's limits. A ball on a flat surface has a contact point that is as small as the point of a pin. Ball bearings place the ball in a groove with a curvature that matches the arc of the ball. This spreads the contact point across the curvature of the ball which increases the load the ball can handle without deforming the surface of the ball. A ball bearing with a small ball and shallow grove in the race will not carry as much load as a larger ball running in a deeper groove, but the small ball (which has less contact area) has a lower rolling resistance than the large ball bearing.

Now take into consideration that the contact area is spread from a single point on a flat surface to approximately 1/5 of it's diameter when placed in a groove of the same arc in a shallow groove ball bearing is still supporting the weight on a very narrow point now a line and doubled by an identical contact point on the opposite side of the bearing. With a larger ball and a deeper groove, the load capacity is increased by way of increasing the length of the contact point to perhaps 1/3 the diameter of the ball, but the larger the ball and the deeper the groove, the more prone to breakage the race becomes, so it's a tight rope balancing act to get the exact curvature of the groove to match the arc of the diameter of the ball.

A simpler design is the roller bearing. A cylinder laying on a flat surface has a contact point the width of the point of a pin, but its full length, but a cylinder has more rolling resistance than ball and the ball is more susceptible to damage (flat spot) caused by impact and over loading. While the roller bearing has a higher loading capacity than a ball bearing of a similar mass (a ball bearing of certain ID and OD compared to a roller bearing of the same dimensions), it also has more resistance to movement (inertia).

Ball bearings are a better choice for high speed low load applications while roller bearings are a better choice for high load lower speed applications.

Now consider all the SPECIAL bearings and their specific application. The axle bearing used in early Polaris designs was a simple roller bearing used in opposition. The problem is pre-loading; how much is too much and how much is too little? Fortunately roller bearings are designed for 'side loading' and are forgiving, they perform well over loaded and under loaded, but ball bearings are designed for perpendicular loading and will fail rapidly when side loaded. This is evidenced when you tighten roller bearings - the bearing will function when over over loaded, but it's life will be shortened due to friction caused by the pressure. A ball bearing will resist movement with very little lateral loading due to the direction of force. A roller bearing works equally well in vertical and horizontal positions while ball bearings are intended for carrying horizontal loads. A ball bearing supporting a vertical load will fail quickly.

The SPECIAL ball bearing used in the current crop of Polaris quads are back to back 'lateral' designed bearing. This bearing has the advantage of lower rolling resistance and the ability to be side loaded, but due to it's design and application, has a reduced load carrying capacity.

As a special application bearing, the only way to reduce cost is through material saving (less mass and lower quality steel), labor savings (manufactured by lower paid workers), tooling cost (lower cost machinery), higher production rates (more pieces per hour) and less quality control.

A special design bearing will cost about the same from various manufacturers and may only be available from a single source until the popularity and viability of the design makes it profitable to produce. Some of the special designs commercially available today came from our space program.

The bearings in discussion here whether branded TOYO, NSK, Timken, SKF, NTN, Nachi and some other companies, all produce equal quality bearings. The important thing is design and application. If you use a design for an application it was not designed for may work or last better. Sometimes the acid test is in the field. Use any brand and many brands to determine which last longest vs initial cost. At the end of the test, publish the findings to inform the public of your discovery.

In the short term and local terrain of my locale, I can use the cheapest available and have acceptable performance. In the previously stated Honda situation, I am limited not by cost, but availability. When the bearings in this discussion are discontinued by the distributor and the manufacturer has no outlet for the design, the bearing will no longer be manufactured and there will be a lot of unusable vehicles littering the landscape unless someone can economically modify the unit to be retrofit with a product that is readily available. This is the AFTERMARKET! Thank god for machine shops and machinists.
 
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